Differential area piston pumping system



Dec. 29, 1959 L. GREINER 2,918,791

DIFFERENTIAL AREA PISTON PUMPING SYSTEM Filed Aug. 20, 1956 3 Sheets-Sheet 1 II 11H IIIIIIIIGi-"E um "ml-:-

4N INVENTOR LEONARD GREINER 2 ATTORNEY Dec. 29, 1959 L. GREINER DIFFERENTIAL AREA PISTON PUMPING SYSTEM 3 Sheets-Sheet 2 Filed Aug. 20, 1956 Dec. 29, 1959 L. GREINER 2,918,791

DIFFERENTIAL AREA PISTON PUMPING SYSTEM Filed Aug. 20, 1956 3 Sheets-Sheet 3 H 2 a B\ J N 2 g w 2 O i O\ -2 2 a g \8 2- INVENTOR LEONARD GREINER A I JM 1 ATTORNEY United States Patent DIFFERENTIAL AREA PISTON PUMPING SYSTEM Leonard Greiner, Richmond, Va., assignor to Experiment Incorporated, Richmond, Va., a corporation of Virginia Application August 20, 1956, Serial No. 604,860

Claims. (Cl. 60-355) This invention relates to a pump system and more particularly to a pump system for fluid propellants for reaction motors and the like.

It is an object of the present invention to provide a simplified fluid propellant pump ng system that elimi nates the use of complicated fluid pumping means or the storage of gas at high pressures to inject the fluid propellants into rocket combustion chambers or the like.

Another object of the invention is to provide an improved, compact, and economical fluid propellant rocket whereby high propulsion efficiencies may be obtained through the utilization of fluid fuels.

It is a further object of the invention to provide a fluid fuel pumping system wherein the flow and combustion of the fluid fuel is automatically started and fed at a pre-determined rate into a combustion zone having a fixed size.

Another object is to provide such a device permitting the simple utilization of a fluid gas-generant for pumping the fuel.

A further object is to provide means for pumping fluid propellants in rockets or other missiles and the like in a space-efficient manner.

These and other objects and advantages are provided by the present invention which generally comprises a fluid-containing chamber having an outlet therefrom, a pressure generating chamber, a partition member separating the fluid-containing chamber from the pressure generating chamber movable in a direction toward the outlet from the fluid-containing chamber, a gas generant chamber having an outlet communicating with the pressure generating chamber, and a d fferential area piston transmitting pressure from the pressure generating chamher to the gas generate chamber to effect injection of the gas generate from the gas generant chamber into the pressure generating chamber.

The invention will be more particularly described in reference to the accompanying drawings wherein;

Fig. 1 is a perspective plan view of a rocket incorporating the present invention;

Fig. 2 shows a sectional view through the rocket shown in Fig. 1;

Fig. 3 is a sectional view similar to that shown in Fig. 2 of a modified form of the present invention;

Fig. 4 is a section substantially on line 4-4 of Fig. 3;

Fig. 5 is a sectional view similar to Fig. 2 of a further form of the present invention.

Referring to Figs. 1 and 2, is the shell or casing of a rocket or missile which may be provided with fins or stabilizers 12 at the rear end and a chamber for the reception of instruments or an explosive charge at the forward end 14.

In the rearward portion of the rocket there is provided a combustion chamber 16 provided with a nozzled out let 18 formed by converging diverging wall members 20. Within the combustion chamber there may be provided an igniter 22 for initiating combustion of the rocket fuel 2,918,791 Patented Dec. 29, 1959 when the rocket is propelled by non-spontaneously ig' nitable fuels.

The igniter 22 may comprise, for example, a small charge of black powder, gun powder, or small solid grain 24 and an electric igniter 26 therefor provided with electrical conductors generally indicated at 28.

The combustion chamber 16 is separated from the forward portion of the missile by a rigid partition member 30 having an outlet 32 therein. The outlet 32 is shown in the illustrated forms of the invention as including a nozzle 34 provided with a spring-urged ball check 36 to prevent loss of propellant during storage or shipment.

The casing is also provided with a slidably mounted partiton 38 positioned forwardly of the fixed partition 30, and the shell, the fixed partition 30, and the movable partition 38 defines a chamber 40 adapted to receive and store a fluid propellant for the rocket. In the form of the invention shown in Fig. 2, the fuel chamber is adapted to receive a gaseous or liquid mono-propellant. Monopropellants such as nitromethane, l-nitro-propane, Z-nitro propane, l nitrobutane, normal propyl nitrate or ethyl nitrate may be effectively employed as the propulsion fuel.

The rocket is further provided with a second fixed partition member 42 forwardly of the slidable partition 38. Partition member 42 comprises a transverse wall 44 provided with annular boss 48 within which a differential area piston 50 is adapted to slide. The head of the differential piston 52 defines with the transverse wall 44 and the annular boss 48 a chamber 54 adapted to receive a gas generant.

The differential piston 50 is provided with an outlet 56 which communicates with the gas generant stored in chamber 54 and a pressure generating chamber 58 positioned between the piston 50 and the slidably mounted partition 38. The outlet 56 may include, as shown in the drawings, a valved nozzle of the type hereinbefore described with reference to outlet 32.

The differential piston 50 includes a wall member 60 provided with an outlet 62 having a shield 64. The space between the piston head 52, and walls 60 and 66 of the piston provides a zone for the combustion, decomposition and/or expansion of the gas generant issuing from chamber 54.

Within the combustion or gas-forming zone 68 is an igniter 70 which may take the form of the igniter 22 hereinbefore described.

As shown in the drawings the movable partition 38, and the differential area piston may be provided with suitable gaskets or piston rings 37 to prevent leakage of fuel or gas generant. Further, the casing 10 has one or more openings 72 communicating with the space 74 between the outer surface of the piston wall 66 and the inner surface of the casing to prevent entrapment of air in said space upon the forward motion of the piston 50.

In the form of the invention shown in Fig. 2 the gas generant may comprise a fluid mono-propellant of the liquid or gaseous type, a liquid having a low boiling point or a liquid which decomposes into gaseous products such as ethylene oxide. Thus in this form of the invention the gas generant may be the same as the primary fuel contained in chamber 40.

Where the gas-generant liquid is a low boiling liquid which expands into the gaseous form the igniter 70 is replaced with a flare adapted to burn throughout the operating cycle of the pump to supply the heat necessary to convert the liquid into the gaseous form. A simple thermit type flare would be satisfactory.

In operation of the rocket shown in Fig. 2, the chamber 40 is filled with a liquid mono-propellant and chamber 54 is filled with a liquid gas generant which may be the same as the propelling fuel in chamber 40. The igniter 70 is set off to produce heat and pressure in chamber 68. The augmented pressure is transmitted through opening 62 in wall 60 of the differential piston 50 into the pressure generating chamber 58. The increase in pressure in the pressure generating chamber 58 forces the differential area piston 50 into chamber 54. The liquid gas generant in chamber 54 is urged into the chamber 68 through the valved outlet 56 by the forward movement of the piston 50. The liquid gas generant entering chamber 68 expands into a gaseous form, decomposes into gaseous products, or in the case of a mono-propellant is converted into products of combustion. The gaseous products formed by the gas generant in chamber 68 pass through the opening 62 into the pressure generating chamber 58 thereby perpetuating the process of injecting gas generant through the outlet nozzle 56 into the pressure generating chamber. Simultaneously with the movement of the differential area piston 50 toward the front wall 44 of the gas generant chamber 54, the slidably mounted partition 38 forming the forward wall of the primary fuel chamber 40 is caused to move in the direction of the primary fuel outlet nozzle 32. The liquid propellant in chamber 40 issuing into the combustion chamber 16 is caused to be ignited by igniter 22 which may have been set off simultaneously with the igniter 70 in the chamber 68. The combustion of the mono-propellant in the combustion chamber 16 produces rocket thrust in passing through the outlet 18 of the missile.

From the foregoing description of the operation of this form of the invention it will be seen that the gas generant is automatically pumped into the pressure generating chamber 58 and the primary propulsion fuel is automatically pumped into the primary combustion chamber 60, in an efficient, uniform and highly satisfactory manner.

Where the liquid or the gas generant in chamber 54 is ethylene oxide it has been found that from about 30 to 35 cubic feet of gas at standard conditions is obtained from only about 2 lbs. of gas generant in the chamber 54 whereby only a small area of the entire rocket or missile is required for the efficient and smooth pumping of the primary propulsion fuel into the rocket combustion chamber.

The present invention may be effectively employed with substantially any combination of mono-propellant, or bi-propellant propulsion fuels with substantially any combination of mono-propellant, bi-propellant, gas generant fuel. In Fig. 3 of the drawings a modified form of the present invention is shown wherein a bi-propellant fuel system is employed with a single chamber adapted to receive a gas generant.

Referring to Fig. 3, the casing of the rocket is provided with a fixed partition 80 positioned forwardly of the primary combustion chamber 16. This partition member has a plurality of outlet nozzles 32 therein which may be constructed as shown in Fig. 2. of the drawings. The nozzles 32 of Fig. 3 are positioned to direct bi-propcllant fuels from concentric fuel storage compartments 82 and 84 so that the fuels issuing from the nozzles 32 are mixed and burned in the combustion chamber 16.

The bi-prope|lant fuels for this form of the invention are maintained separately by means of a cylindrical partition member 86 which extends from the inner surface of partition member 80 forwardly throughout the length of the fuel storage compartment. In order to pump the liquid from compartments 82 and 84 simultaneously, a circular partition member 85 is slideably mounted within the tubular compartment formed by the wall of cylinder 86 while an annular slideably mounted partition 90 engages the outer surface of the cylindrical partition member 88 and the inner surface of the shell 10 forming the outer wall of fuel compartment 82. The slideably mounted partitions or pistons 88 and 90 may be provided with gaskets or piston rings 37 as hereinbefore described with reference to Fig. 2.

A gas generant compartment 54, a differential area piston 50, outlet nozzle 56, igniter 70 and pressure generating chamber 58 are provided forwardly of the upper end of the primary fuel compartments 82 and 84 as hereinbefore described with reference to the embodiment of the invention shown in Fig. 2.

In the form of the invention shown in Fig. 3, any suitable bi-propellant fuels may be stored in the compartments 82 and 84. Examples of suitable fuels are propane, hydrazine or aniline provided with oxidizers such as fuming red nitric acid or liquid oxygen. When the bi-propellant comprises aniline and fuming red nitric acid, the igniter 23 in the primary combustion chamber 16 may be eliminated as the fuel and oxidizer are spontaneously ignited upon mixing.

In Fig. 5 of the drawing a further modification of the present invention is shown wherein a bi-propellant gas generant is employed in combination with a rocket having a mono-propellant propulsion generating fuel. In Fig. 5 the rocket 10 is shown as having a fixed partition member 30 with a valved outlet 32 for directing fuel into the primary combustion chamber 16 from which the products of combustion issue through outlet nozzle 18. The combustion chamber has a typical igniter 22 and the single fuel storage compartment 40 has a slidably mounted partition or piston member 38 positioned upstream of the fixed partition member 30.

In order to pump the liquid fuel contained in chamber 40, with a bi-propellant gas generant, a differential area piston is provided for simultaneous displacement into plural gas generant storage compartments 102 and 104. The piston 100 is constructed with a head 106 provided with valved outlets 108 directed into an inner combustion chamber 110 and a second head 112 connected to the piston head 106 by a cylindrical boss 114. The boss 114 has a central bore 116 therethrough causing spring urged valve means 118 similarly in construction to the valve means in the nozzles 32 and 108.

In this form of the invention the gas generant chambcrs 102 and 104 and the outlet nozzles therefrom are proportioned in size to accommodate and deliver the correct amounts of fuel and oxidizer and therefore their size and shape would differ with different gas generant liquids.

As in the other forms of the present invention, suitable packing means or rings 37 are provided on the piston and movable partition 38 to prevent leakage of the fuel during storage or operation of the rocket.

The rearward end of the differential area piston 100 is substantially identical to the rearward portions of the differential area pistons 50 shown in Figs. 2 and 3 of the drawing, and thus includes a well member 120 having a shielded outlet 122 through which the products of combustion of the bi-propellant fuels carried in gas generant compartments 102 and 104 may issue into the pressure generating compartment 58 whereby the movable partition 38 for the primary combustion chamber and the differential area piston are urged toward the rearward and forward ends of the rocket, respectively.

in operation of the form of the invention shown in Fig. 5, primary fuel storage tank 40 is filled with a suitable mono-propellant fuel; gas generant compartment 102 is filled with. for example, an oxidizer such as red fuming nitric acid; and gas generant compartment 104 is filled with a suitable fuel, such as aniline. When the igniter 60 is set oil the pressure developed thereby in chamber 58 forces the heads 106 and 112 of differential area piston into chambers 102 and 104, respectively. The liquid displaced by piston head 106 issues from valved nozzles 108 while the liquid displaced by piston head 112 passes through the passage 116, the valve 118 and into chamber 110 where the liquids are mixed. The pressure developed by the combustion of the mixed oxidizer and fuel further aetuates the differential area piston 100 and urges the movable partition member 38 further into the chamber 40 forcing the primary mono-propellant contained in said chamber into the primary combustion chamber 16 where the fuel is ignited by igniter 22 as hereinbefore set forth.

While the present invention has been primarily described with reference to the use of the present invention in combination with reaction propulsion rockets it will be seen that the pumping system may readily be employed for other uses. For example, the system may be used to pump fuels for the operation of turbines by the substitution of a conventional turbine stator and rotor for the nozzled outlet from the rocket combustion chambers shown in the application drawings.

From the foregoing description it can readily be seen that the present invention provides new and useful improvements in reaction propulsion motors and pumps therefor which fully accomplish the aims and objects hereinbefore set forth.

I claim:

1. A propellant agent pumping system comprising a combustion chamber having an exhaust outlet communicating therewith, a primary propellant agent chamber having a propellant agent outlet communicating with the combustion chamber, a pressure generating chamber, a partition member sealing the primary propellant agent chamber from the pressure generating chamber, said partition member being movable in a direction toward the propellant agent outlet from the primary propellant agent chamber, a gas generant chamber having an outlet communicating with the pressure generating chamber, a differential area piston, the larger surface area of said differential area piston being in communication with the pressure generating chamber and movable in a direction opposite to the direction of movement of said partition member, the smaller surface area of said differential area piston forming one wall of the gas generant chamber, the pressure generated within the pressure generating chamber being effective to move the differential area piston and the partition member in opposite directions to effect injection of the gas generant into the pressure generating chamber and primary propellant agent from the primary propellant agent chamber into the combustion chamber.

2. The invention defined in claim 1 wherein the primary propellant agent chamber includes plural chambers each having a propellant agent outlet communicating with the combustion chamber.

3. The invention defined in claim 2 wherein the plur-al propellant agent chambers comprise concentric chambers each being provided with a separate partition member sealing its respective propellant agent chamber from the pressure generating chamber.

4. A propellant agent pumping system including a combustion chamber having an exhaust nozzle communicating therewith, a primary propellant agent chamber having a propellant agent outlet communicating with the combustion chamber, a pressure generating chamber, a partition member sealing the primary propellant agent chamber from the pressure generating chamber, said partition member being movable in a direction toward the propellant agent outlet from the primary propellant agent chamber, plural gas generant chambers, each of said gas generant chambers having an outlet communicating with the pressure generating chamber, a differential area piston transmitting pressure from the pressure generating chamber to each of the gas generant chambers to effect injection of the gas generant from each of the gas generant chambers into the pressure generating chamber, the larger surface area of said differential area piston being in communication with the pressure generating chamber and being movable in a direction opposite to the direction of movement of said partition member, the smaller surface areas of said piston forming one wall of each of said gas generant chambers.

5. A propellant agent pumping system comprising a combustion chamber having an exhaust outlet communicating therewith, a single primary propellant agent chamber having a propellant agent outlet communicating with the combustion chamber, a pressure generating chamber, a single partition member sealing the primary propellant agent chamber from the pressure generating chamber, said single partition member being movable in a direction toward the propellant agent outlet from the primary propellant agent chamber, a gas generant chamber having an outlet communicating with the pressure generating chamber, a differential area piston transmitting pressure from the pressure generating chamber to the gas generant chamber to effect injection of the gas generant from the gas generant chamber into the pressure generating chamber, the larger surface area of said differential area piston being in communication with the pressure generating chamber and being movable in a direction opposite to the direction of movement of said partition member, the smaller surface area of said differential area piston forming one wall of the gas generant chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,671,312 Roy Mar. 9, 1954 2,789,505 Cumming et a1 Apr. 23, 1957 FOREIGN PATENTS 1,100,118 France Mar. 30, 1955 695,048 Great Britain Aug. 5, 1953 

